MXR Blue Box mods

[BassJunkie730]

So I got this schematic in response to a thread from Malekko




and I'll be working from this schematic from Tonepad to route my changes - but I'll specifically use the board in whatever box I acquire.



This thread will track my experiences doing this mod.

My goals:

- more bass friendly
- only one octave down instead of two
- less of an "8-bit sound"
- clean up the fuzz
- bring box up to unity gain - or install a volume trim pot.

How I'm going to get there?

- change the divider to two instead of four via Malekko's mod above.
- change the diodes to rectifier type 1N4002s
- change "c9" or "c11" depending on the schem - or take it out completely for volume boost.
- change 4558 chip to an OPA2134 and increase the bias for extended bandwidth and higher headroom.
- change C1 to .1 or 1uf
- investigate changes to C2, C4, C10, C13 for improved bass response.


I'm looking to change the Blue Box into something a bit different. I do not mind changing some hallmarks of the box (particularly the lo-fi sound and the two octaves down)

Sure, one could throw this one into a loop and blend it in stock

But perhaps there are individuals that really dig the synthy tone of the pedal and would like to reign it in.

thoughts?

[rratajski]

I am VERY interested to hear the changes!!!

I love Mega Man, but not in my bass.

[whoatherechunk]

nice. very nice.

[RickenBoogie]

Finally. Good task at hand, that pedal NEEDS some taming.

[sonicvi]

Originally Posted by BassJunkie730

How I'm going to get there?

- change the divider to two instead of four via Malekko's mod above.
- change the diodes to rectifier type 1N4002s
- change "c9" or "c11" depending on the schem - or take it out completely for volume boost.
- change 4558 chip to an OPA2134 and increase the bias for extended bandwidth and higher headroom.
- change C1 to .1 or 1uf
- investigate changes to C2, C4, C10, C13 for improved bass response.

A couple of thoughts

1. Don't know what difference changing the diodes that would make as they aren't involved in the clipping.

2.the object of the opamp is first to increase the signal level in IC1A and then to distort the signal like hell (turned into a square wave) by IC1B which is configured as a Schmitt Trigger. The 4013 is looking for the squarest wave it can get to divide with the most accuracy. Increasing headroom will cause less clipping by IC1B which could have an adverse effect on tracking (which isn't stellar in the BB to begin with). If you want a less 8-bitish sound you'd probably have better luck messing around with the filtering and the thresholds of the two transistor "gates" that cause the abrupt synthy cutoff.

There are some really good threads about the Blue Box at diystompboxes.com that might give you some better insight into how to proceed.

[whoatherechunk]

any progress?

[rratajski]

Mega Man stole his powers and blasted him away...

[whoatherechunk]

HAHAHAHAHA

[Swimming Bird]

Ideally you shouldn't take away any of the original's capabilities. I think a lot of the joy in pedals is skating that edge of usability and taming it to your standards may be too far for others who may otherwise be interested.

By the by, I circuit bent my BB and ended up bypassing the gate and boosting the volume.

[whoatherechunk]

are there any clips or videos of the blue box on bass?

[Deluge Of Sound]

I use a blue box on bass all the time.

Unfortunately, I'm two states away from my gear, so clips aren't going to be a possibility for a couple of weeks.

[Mads]

Subscribed.

Hoping for updates

[rcubed]

I tried a Blue Box with bass and didn't care for it. I'd rather have a Fuzz Factory for weird fuzz. I did buy a Devi Ever Bit, a pedal I'd consider in the same category as the Blue Box and Fuzz Factory and have been surprised with it so far.

More bass is almost always a result of increasing the size of the capacitors. But there can potentially be bad results in doing so. Capacitors allow more signal to pass (while still blocking DC) and will lower the cutoff frequency in a low or high pass filter.